1. Field of the Invention
The present invention relates to a printing apparatus which performs printing by transporting a liquid onto a printing medium such as a recording paper
2. Description of the Related Art
A printing apparatus which includes an ink-jet head discharging an ink on to a printing medium, has been hitherto used widely as a printing apparatus which performs printing on various printing media such as a recording paper. Here, printing apparatuses with various structures of the ink-jet head are available, and a printing apparatus in which an ink-jet head includes a channel unit provided with a plurality of individual ink channels including a pressure chamber communicating with a nozzle, and a piezoelectric actuator which applies a pressure to an ink in the pressure chamber is an example of such printing apparatus (refer to U.S. Pat. No. 6,926,382 (corresponding to Japanese Patent Application Laid-open No. 2003-326712)).
A general piezoelectric actuator includes a plurality of individual electrodes corresponding with a plurality of pressure chambers, a common electrode facing the individual electrodes, and a piezoelectric layer sandwiched between the individual electrode and the common electrode, which is formed by a piezoelectric material such as lead zirconate titanate (PZT). Moreover, when a drive voltage is supplied to a predetermined individual electrode, an electric field is generated in a portion of the piezoelectric layer sandwiched between the individual electrode and the common electrode. As the electric field is generated, the piezoelectric layer is deformed partially, and with the deformation of the piezoelectric layer, a pressure is applied to the ink in the pressure chamber. As the pressure is applied to the ink, the ink is discharged from the nozzle communicating with the pressure chamber.